CVE-2017-15090 in Recursor
Summary
by MITRE
An issue has been found in the DNSSEC validation component of PowerDNS Recursor from 4.0.0 and up to and including 4.0.6, where the signatures might have been accepted as valid even if the signed data was not in bailiwick of the DNSKEY used to sign it. This allows an attacker in position of man-in-the-middle to alter the content of records by issuing a valid signature for the crafted records.
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Analysis
by VulDB Data Team • 02/02/2023
The vulnerability identified as CVE-2017-15090 represents a critical flaw in the DNSSEC validation mechanism of PowerDNS Recursor versions 4.0.0 through 4.0.6. This issue fundamentally undermines the security assurances provided by DNSSEC by allowing malformed signatures to be accepted as valid, creating a significant attack vector for man-in-the-middle operations. The vulnerability stems from improper validation of the bailiwick constraint within DNSSEC signature verification processes, which should ensure that signed records fall within the authoritative zone of the DNSKEY used for signing.
The technical implementation flaw resides in the DNSSEC validation logic where the recursor fails to properly verify that the signed data originates from the same zone as the DNSKEY used to validate the signature. This omission creates a scenario where an attacker can craft malicious DNS records with valid signatures by leveraging DNSKEYs from different zones, effectively bypassing the intended security boundaries. The vulnerability specifically affects the signature validation component of DNSSEC, where the system should enforce strict zone boundary checks but instead accepts signatures that appear valid but originate from unauthorized zones.
From an operational standpoint, this vulnerability exposes systems to active attack scenarios where adversaries can manipulate DNS responses without detection. The impact extends beyond simple data corruption as it undermines the entire trust model that DNSSEC is designed to provide, allowing attackers to redirect traffic to malicious endpoints while maintaining the appearance of legitimate DNS responses. This type of attack can be particularly devastating in enterprise environments where DNS resolution forms the foundation of network communication and security infrastructure.
The security implications align with CWE-284 Access Control Bypass and can be mapped to ATT&CK technique T1071.004 Application Layer Protocol DNS for its exploitation through DNS protocol manipulation. Organizations using affected PowerDNS Recursor versions face significant risk of DNS spoofing attacks that could compromise network security, enable data exfiltration, or redirect users to malicious websites. The vulnerability's exploitation requires minimal network proximity and can be executed by attackers positioned between clients and authoritative DNS servers, making it particularly dangerous in public or shared network environments.
Mitigation strategies should prioritize immediate upgrade to PowerDNS Recursor version 4.0.7 or later, which contains the patched validation logic. Organizations should also implement additional monitoring for unusual DNS response patterns and consider deploying DNSSEC-aware network security tools that can detect malformed DNSSEC signatures. Network administrators should review their DNSSEC configurations and ensure that proper zone boundary validation is enforced. The fix addresses the core validation issue by implementing proper bailiwick checking that verifies the relationship between signed data and the DNSKEY used for signature validation, restoring the intended security guarantees of DNSSEC implementations.